UNIT 5 GENETICS BY DR. SADAKAT BASHIR.pptx

SERVICES RELATED TO GENETICS

1. UNIT 5 GENETICS BY Dr. SADAKAT BASHIR (BDS, MPH)

2. GENETIC TESTING Genetic testing involves analyzing an individual’s DNA to identify genetic disorders, mutations or variations. Genetic testing is a process that analyzes an individual's DNA, chromosomes, or proteins to detect changes, variants, or mutations that could indicate or cause a genetic disorder, assess disease risk, or influence treatment and medication effectiveness. 

3. TYPES OF GENETIC TESTING 1. Diagnostic Testing Purpose: To confirm or rule out a specific genetic or chromosomal condition. When used: When symptoms of a genetic disorder are already present. Example: Testing for cystic fibrosis or sickle cell anemia.

4. 2. Predictive (or Presymptomatic ) Testing Purpose: To detect mutations that increase the risk of developing a disorder later in life. When used: In healthy individuals with a family history of a genetic disorder. Example: Testing for Huntington’s disease or BRCA1/BRCA2 for breast cancer risk.

5. 3. Carrier Testing Purpose: To identify individuals who carry one copy of a gene mutation that could cause a disorder if passed to a child. When used: Before or during pregnancy. Example: Carrier screening for thalassemia or cystic fibrosis.

6. 4. Prenatal Testing Purpose: To detect genetic abnormalities in a developing fetus . Methods: Amniocentesis Chorionic villus sampling (CVS) Example: Detecting Down syndrome or spina bifida.

7. 5. Newborn Screening Purpose: To identify genetic or metabolic disorders soon after birth. When used: Routine test done in hospitals after delivery. Example: Screening for phenylketonuria (PKU) or congenital hypothyroidism.

8. 6. Preimplantation Genetic Testing (PGT) Purpose: To detect genetic changes in embryos created through IVF (in vitro fertilization) before implantation. Example: Avoiding transfer of embryos with cystic fibrosis mutation.

9. 7. Forensic Genetic Testing Purpose: To identify individuals for legal or criminal investigations. Example: DNA fingerprinting for crime scene analysis or paternity testing.

10. METHODS OF GENETIC TESTING Genetic testing methods are laboratory techniques used to analyze DNA, RNA, chromosomes, or proteins to detect genetic variations or mutations. Different methods are used depending on the type of disorder or the size of the genetic change.

11. 1. Molecular Genetic Tests (DNA Tests) These tests study small changes in genes — such as mutations, deletions, or duplications — at the DNA level. a. Polymerase Chain Reaction (PCR) Purpose: Amplifies (copies) a specific DNA segment for analysis. Used for: Detecting known mutations, infectious agents, or carrier status. Example: Detecting sickle cell mutation or COVID-19 testing (same principle).

12. b. DNA Sequencing Purpose: Determines the exact order of bases (A, T, G, C) in a gene. Types: Sanger sequencing – for single genes. Next-Generation Sequencing (NGS) – for multiple genes or whole genomes. Example: BRCA gene sequencing for breast cancer risk.

13. c. Restriction Fragment Length Polymorphism (RFLP) Purpose: Uses restriction enzymes to cut DNA at specific sites; variation in fragment length indicates mutation. Example: Detecting β- globin gene mutation in sickle cell anemia . d. Real-Time PCR ( qPCR ) Purpose: Measures DNA or RNA in real time; used for gene expression or viral load analysis. Example: HIV viral load testing.

14. 2. Cytogenetic Tests (Chromosome Tests) These methods analyze whole chromosomes to find large changes (extra, missing, or rearranged parts). a. Karyotyping Purpose: Visualizes chromosomes under a microscope to detect number or structure abnormalities . Example: Detecting Down syndrome (Trisomy 21) or Turner syndrome (45,X).

15. b. Fluorescence In Situ Hybridization (FISH) Purpose: Uses fluorescent DNA probes to detect specific genes or chromosome regions. Example: Detecting microdeletions or translocations (like in leukemia ).

16. c. Comparative Genomic Hybridization (CGH) / Array CGH Purpose: Detects copy number variations (CNVs) — gains or losses of DNA segments across the genome. Example: Diagnosing developmental delays or autism.

17. 3. Biochemical Genetic Tests These tests study proteins or metabolites to detect abnormalities caused by genetic mutations. Purpose: Measure enzyme activity or metabolic products. Example: PKU (Phenylketonuria) screening — measures phenylalanine levels. Tay-Sachs disease — checks enzyme hexosaminidase A.

18. 4. Epigenetic Testing Purpose : Examines changes in gene expression caused by chemical modifications (like DNA methylation), not DNA sequence changes. Example: Used in cancer diagnosis and research.

19. 5. Whole Genome and Whole Exome Sequencing Whole Genome Sequencing (WGS): Reads the entire DNA sequence. Whole Exome Sequencing (WES): Reads only protein-coding regions (exons) — 1–2% of genome but 85% of disease-causing mutations. Example: Used for rare or undiagnosed genetic conditions.

20. APPLICATIONS OF GENETIC TETSING Genetic testing has become an essential tool in medicine, research, forensics, and public health . It helps in identifying genetic disorders, guiding treatment, and preventing disease transmission.

21. 1. Diagnosis of Genetic Disorders Used to confirm or rule out a suspected genetic disease. Helps in early and accurate diagnosis. Examples: Diagnosing cystic fibrosis, sickle cell anemia , or muscular dystrophy. Identifying chromosomal abnormalities like Down syndrome.

22. 2. Predictive and Presymptomatic Testing Detects gene mutations that may cause diseases later in life. Enables early prevention, monitoring, or lifestyle changes. Examples: BRCA1/BRCA2 testing for breast and ovarian cancer risk. Huntington’s disease testing before symptoms appear.

23. 3. Carrier Screening Identifies individuals who carry one copy of a defective gene that could be passed to their children. Helps in family planning and genetic counseling. Examples: Thalassemia carrier testing. Cystic fibrosis carrier screening.

24. 4. Prenatal and Newborn Testing Prenatal testing: Detects genetic abnormalities in the fetus . Newborn screening: Detects treatable genetic or metabolic disorders soon after birth. Examples: Down syndrome detection (prenatal). PKU or congenital hypothyroidism ( newborn ).

25. 5. Pharmacogenomic Applications Studies how genes affect a person’s response to drugs . Helps doctors choose the right medicine and dosage for each individual. Examples: CYP2C19 gene testing before prescribing clopidogrel . Warfarin dose adjustment based on genetic profile.

26. 6. Forensic and Identity Testing Used for criminal investigations , paternity testing, and disaster victim identification. Relies on DNA fingerprinting techniques. Examples: Identifying suspects in a crime scene. Establishing biological relationships.

27. 7. Research and Gene Discovery Helps scientists identify new genes and understand how mutations cause diseases. Contributes to the development of gene therapy and personalized medicine. Example: Human Genome Project and disease gene mapping.

28. 8. Cancer Detection and Management Detects genetic mutations in tumor cells to guide diagnosis and treatment. Helps in targeted therapy selection . Examples: HER2 testing in breast cancer. KRAS or EGFR mutation testing in lung cancer.

29. 9. Public Health Applications Helps in population screening , disease prevention , and policy development . Supports programs for thalassemia control or newborn screening.

30. BENEFITS AND LIMITATIONS OF GENETIC TESTING Genetic testing provides valuable information about a person’s genes, health risks, and inherited traits , but it also has limitations and ethical concerns .

31. BENEFITS OF GENETIC TESTING 1. Early Diagnosis and Prevention Detects genetic disorders before symptoms appear . Helps in early treatment or preventive measures. Example: Early detection of BRCA mutation → preventive cancer screening.

32. 2. Personalized Treatment Helps doctors choose specific medicines or doses based on a person’s genes ( pharmacogenomics ). Improves treatment safety and effectiveness. Example: Tailoring chemotherapy drugs based on tumor genetics.

33. 3. Informed Family Planning Identifies carriers of inherited disorders (like thalassemia, cystic fibrosis). Helps couples make informed reproductive choices through genetic counseling or prenatal testing .

34. 4. Reduced Disease Risk Individuals with genetic risk can modify lifestyle , monitor health, or take preventive action. Example: Lifestyle modification in people with risk for heart disease or diabetes.

35. 5. Newborn Health and Early Management Newborn screening detects metabolic or genetic conditions early → timely treatment prevents complications. Example: PKU detection and dietary management.

36. 6. Supports Medical Research Helps identify new disease genes and develop gene therapy or targeted drugs . Advances personalized medicine . 7. Forensic and Identity Benefits Useful in criminal identification , paternity testing , and disaster victim identification .

37. LIMITATIONS OF GENETIC TESTING 1. Incomplete Understanding Some test results may be uncertain or show variants of unknown significance (VUS) . Not all genetic variants are fully understood.

38. 2. Emotional and Psychological Impact Positive results can cause anxiety, fear, or guilt . Negative results may lead to false reassurance . 3. Ethical and Privacy Concerns Risk of genetic discrimination in jobs or insurance if results are misused. Privacy of genetic data is a serious concern.

39. 4. Limited Predictive Value Having a gene mutation doesn’t always mean the person will develop the disease — environment and lifestyle also play roles. 5. Cost and Accessibility Some tests are expensive and not available everywhere , especially advanced sequencing methods.

40. 6. Potential Family Conflicts Results can affect not only the individual but also family members (e.g., revealing carrier status or non-paternity). 7. No Cure for Some Genetic Disorders Even if detected early, many genetic diseases have no cure — only supportive treatment.

41. Benefits Limitations Early disease detection May give uncertain results Personalized treatment Emotional stress and anxiety Informed family planning Privacy and ethical issues Preventive health measures Limited predictive value Newborn screening benefits High cost of advanced tests Research and gene therapy Possible family or social impact Forensic use No cure for many disorders

42. GENE THERAPY Definition: Gene therapy is a medical technique that involves modifying or replacing faulty genes to treat or prevent diseases. It aims to correct the underlying genetic problem rather than just treating the symptoms.

43. Purpose of Gene Therapy To replace a defective gene with a healthy one. To inactivate a faulty gene that is causing problems. To introduce a new or modified gene to help fight a disease.

44. APPLICATIONS OF GENE THERAPY Inherited Disorders : Gene therapy can be used to treat inherited disorders such as sickle cell anemia and cystic fibrosis. Cancer: Gene therapy can be used to treat cancer by introducing genes that help kill cancer cells. Genetic disorders : Gene therapy can be used to treat genetic disorders, such as muscular dystrophy and Huntington’s disease, Viral infections : Gene therapy can be used to treat viral infections such as HIV and hepatitis.

45. TYPES OF GENE THERAPY 1 . Somatic Cell Gene Therapy Genes are inserted into body (somatic) cells like bone marrow, liver, or muscle cells. Changes affect only the treated person , not their offspring. Example: Treatment for SCID (Severe Combined Immunodeficiency ).

46. 2. Germline Gene Therapy Genes are inserted into sperm, egg, or embryo cells . Changes are heritable and passed to the next generation. Not allowed in humans due to ethical and safety concerns.

47. METHODS / TECHNIQUES OF GENE THERAPY a . Gene Addition (Replacement) A normal gene is inserted to replace a defective one. ➡️ Example: Adding a normal CFTR gene in cystic fibrosis. b. Gene Silencing A harmful gene is "switched off" using small RNA molecules (RNA interference). ➡️ Example: Used in some cancer therapies.

48. c. Genome Editing (CRISPR-Cas9) Modern technique that precisely cuts and edits specific DNA sequences. ➡️ Example: Used in research for correcting mutations in sickle cell anemia. d. Suicide Gene Therapy In cancer, a gene is inserted that makes tumor cells sensitive to a particular drug, killing them when the drug is given.

49. VECTORS USED IN GENE THERAPY Vectors are vehicles used to deliver the therapeutic gene into target cells. Type Description Example Viral vectors Modified viruses used to carry genes safely into cells Adenovirus, Retrovirus, Lentivirus Non-viral vectors Safer methods like liposomes, nanoparticles, or direct DNA injection Liposomes, CRISPR plasmids

50. STEPS IN GENE THERAPY Identify the defective gene. Prepare a normal copy of the gene. Insert it into a suitable vector. Deliver it into the target cells/tissues. Monitor for expression and therapeutic effect.

51. ADVANTAGES Targets the root cause of disease. Long-term or permanent effect possible. Can reduce need for lifelong medication. Useful for rare genetic disorders .

52. LIMITATIONS / RISKS Possible immune reactions to viral vectors. Risk of inserting genes in the wrong location (may cause cancer). High cost and complex technology. Ethical issues, especially with germ line therapy.

53. FUTURE OF GENE THERAPY Advances in technology : Advances in technology, such as CRISPR/Cas9, are improving the efficiency and accuracy of gene therapy. Increased funding : Increased funding for gene therapy research is helping to advance the field. Growing demand : Growing demand for gene therapy is driving innovation and investment in the field. Regulatory frameworks : Regulatory frameworks are evolving to accommodate the growth of gene therapy.

54. GENETIC COUNSELLING Genetic counseling is a process that helps individuals or families understand and adapt to the medical, psychological, and social implications of genetic disorders. It provides information, support, and guidance about inherited conditions and the chances of passing them to offspring.

55. Aims / Objectives of Genetic Counseling To explain the nature and cause of a genetic disorder. To assess the risk of recurrence in the family. To inform about available testing, treatment, and prevention options. To help individuals make informed decisions about reproduction or medical care. To provide emotional and psychological support to affected fa

56. TYPES OF GENETIC COUNSELING 1 . Prospective (Pre-conception) Counseling Given before pregnancy to couples with a family history of genetic disease or consanguinity (blood relation). Helps in planning safe conception or avoiding risky unions. Example: Thalassemia carrier screening before marriage.

57. 2. Retrospective (Post-conception) Counseling Given after the birth of a child with a genetic disorder. Focuses on explaining causes, risks of recurrence, and future options. Example: Counseling after birth of a Down syndrome baby.

58. 3. Prenatal Counseling Given during pregnancy if there is risk of fetal abnormality. Guides on prenatal testing (amniocentesis, CVS) and possible interventions. 4. Postnatal Counseling Provided to families after delivery to discuss newborn screening results, management, and recurrence risk. 5. Family Counseling Involves extended family members when the disorder affects multiple relatives.

59. STEPS OF GENETIC COUNSELING Information Collection Family history (pedigree), medical reports, lab tests. Risk Assessment Calculation of recurrence risk using genetic principles. Communication of Information Explain the genetic basis, inheritance pattern, and possible outcomes in simple language.

60. Decision Support Help the family make informed reproductive or medical decisions (non-directive counseling). Follow-up and Support Continuous emotional, medical, and social guidance.

61. INDICATIONS (When Genetic Counseling is Needed) Family history of genetic or inherited diseases . Consanguineous marriage. Recurrent miscarriages or stillbirths. Infertility or birth defects in previous pregnancies. Advanced maternal age (>35 years). Abnormal prenatal test results.

62. BENEFITS OF GENETIC COUNSELING Helps families understand genetic risks. Promotes early diagnosis and prevention. Assists in informed reproductive decisions. Reduces emotional stress through education and support. Improves public health awareness of inherited diseases.

63. LIMITATIONS Cannot prevent all genetic diseases. Sometimes risk estimates are uncertain. May cause emotional anxiety or guilt. Dependent on availability of accurate testing. Ethical and cultural issues may affect decisions.

64. ROLE OF A GENETIC COUNSELOR Trained professional who: Interprets family and medical histories. Educates patients about inheritance and testing. Offers support for decision-making. Coordinates genetic testing and follow-up care.

65. SKILLS AND QUALIFICATIONS OF GENETIC COUNSELORS Masters degree in genetic counseling : A graduate degree in genetic counseling or a related field. Certification: Certification by the American Board of Genetic Counseling (ABGC). Clinical Experience : Experience working in a clinical setting with patients and families. Communication Skills : Strong communication and interpersonal skills to effectively counsel patients and families.

66. LEGAL AND ETHICAL ISSUES IN GENETICS Genetics has revolutionized medicine, but it also raises legal, ethical, and social challenges . These issues arise in areas like genetic testing, counseling, privacy, and gene therapy.

67. Major Ethical Issues a . Privacy and Confidentiality Genetic information is highly personal and may reveal risks for family members. Ethical concern: Who should have access to this data — patients, doctors, employers, or insurance companies? Laws like the Genetic Information Nondiscrimination Act (GINA, 2008, USA) protect individuals from misuse.

68. b. Informed Consent Individuals must give voluntary and informed consent before undergoing genetic testing. They should understand the purpose, benefits, and risks of the test. c. Genetic Discrimination Fear of discrimination in employment or health insurance based on genetic results. Legal safeguards are needed to prevent this misuse.

69. d. Psychological Impact Knowledge of carrying a disease gene may cause anxiety, depression, or guilt . Proper genetic counseling is essential to support emotional well-being.

70. e. Reproductive Choices Prenatal or preimplantation testing may influence decisions about pregnancy . Raises questions about selective abortion , designer babies , and eugenics (improving genes by selection).

71. f. Genetic Modification and Gene Therapy Ethical concerns about altering human DNA , especially germline editing (changes passed to offspring). Debate between potential medical benefits vs moral and social consequences .

72. Legal Issues a . Ownership and Patenting of Genes Controversy over whether human genes can be patented . Legal rulings (e.g., Association for Molecular Pathology vs Myriad Genetics , 2013) prohibit patenting naturally occurring genes .

73. b. Data Protection and Genetic Databases Genetic databases (like biobanks ) require strict data protection laws . Unauthorized sharing or hacking of genetic data is a legal offense in many countries .

74. c. Regulation of Genetic Testing Only certified laboratories should perform tests. Misleading or direct-to-consumer genetic tests without medical guidance can lead to legal consequences . d. Liability Issues Medical professionals may face legal action for wrong interpretation or failure to inform about genetic risks.

75. Social Implications Possible stigmatization of individuals with genetic conditions. Equity and access : advanced genetic services may only be available to the wealthy. Importance of public education and awareness .

76. Ethical Principles in Genetics Autonomy: Right to make one’s own decision about testing or treatment. Beneficence: Acting in the patient’s best interest. Non-maleficence: Do no harm. Justice: Fair access and use of genetic technologies. Genetics holds great promise for improving health, but it must be guided by ethical principles and legal safeguards to ensure fairness, privacy, and respect for human rights.

77. ROLE OF NURSE IN GENETICS Genetics plays an important role in disease prevention, diagnosis, and treatment . Nurses , as frontline healthcare providers, help identify genetic risks , educate families , and support patients throughout the genetic testing and counseling process.

78. Key Roles of Nurses in Genetics a . Health Education Educate individuals and families about: Basic concepts of genetics and heredity Genetic diseases and risk factors Importance of genetic testing and screening Promote awareness about genetic disorders in the community.

79. b. Family History Assessment Collect detailed family health histories (3-generation pedigree). Identify patterns suggesting inherited disorders . Document and communicate findings to the healthcare team.

80. c. Genetic Counseling Support Provide emotional support before, during, and after genetic counseling. Help patients understand test results and implications. Work in collaboration with genetic counselors and physicians.

81. d. Patient Advocacy Protect patient’s rights, privacy, and confidentiality . Ensure informed consent before testing. Advocate for non-discrimination based on genetic information.

82. e. Care and Management Participate in care of patients with genetic disorders (e.g., Down syndrome, sickle cell anemia , cystic fibrosis). Help manage symptoms, coordinate care, and provide ongoing nursing support . Teach families about treatment adherence , nutrition , and lifestyle modifications .

83. f. Ethical and Legal Responsibilities Maintain confidentiality of genetic information. Respect autonomy and cultural beliefs of patients. Follow legal and ethical standards in genetic testing and counseling.

84. g. Research and Continuing Education Participate in genetic research studies . Stay updated with advances in genomics and biotechnology . Attend workshops and training to improve genetic nursing competence .

85. Nurses play a vital role in integrating genetics into health care. They act as educators, advocates, caregivers, and counselors , ensuring that genetic information is used ethically , responsibly , and compassionately to improve patient outcomes.